1. Field Of The Invention
The present invention relates to the field of electrical connectors for coaxial cables and, more particularly, to the class of zero insertion force (ZIF) connectors having receptacles constructed of wire formed in the shape of a single- or double-helix.
In ZIF connectors, pressure between a mating pair of contacts in a male connector part and female receptacle is temporarily withheld during coupling or decoupling, typically by causing a temporary enlargement of the effective inside diameter of the female receptacle so as to disengage the male contact during insertion or removal.
The splicing of two coaxial cable ends requires first removing the insulation from each end, mounting a male fitting on each end, and then screwing the fittings onto a double-ended adapter having opposing female threads in each end. Typically, special tooling is required to apply the fittings, which if improperly applied can result in unreliable performance. The splicing process as presently practiced requires multiple successive operations which are time consuming to execute and require extensive practice to perfect.
There is thus an ongoing and unfulfilled need to easily and efficiently connect and disconnect coaxial cables to each other, whether in a stand-alone device, mounted in a panel, or mounted within electronic equipment.
2. Description Of The Related Art
The use in electrical connectors of single-helix spring coils as variable diameter clamping elements is known in the art. U.S. Pat. No. 4,082,399 to Barkhuff is directed to a ZIF connector wherein a plurality of resilient helical contact members each receive a pin of a multi-pin module.
U.S. Pat. No. 3,518,614 to Nyberg is directed to a receptacle having a plurality of coiled springs attached to and positioned between a pair of rotatable plates. When the plates are rotated with respect to each other in one direction the inner diameters of the coiled springs are simultaneously increased; when rotated in the other direction the diameters are decreased.
U.S. Pat. No. 4,874,909 to Velke, Sr. et al., is directed to a connector for butting the ends of two single-conductor cables within a helically coiled grip element.
U.S. Pat. No. 3,440,333 to Blomstrand is directed to a connector including a helically coiled spring to grip the ends of a plurality of parallel wires without resort to soldering or welding.
U.S. Pat. No. 3,295,872 to Kragle uses a single helical spring to provide a mechanical grip on a coaxial cable. The spring does not contact the outer-conductor of the coaxial cable and thus is not involved in electrical connection.
U.S. Pat. No. 2,427,001 to Hubbel et al., is directed to a panel-mounted receptacle including a coiled spring within a longitudinal chamber which receives and grips a male pin or plug. This is not a ZIF device as there is no provision to enlarge or contract the spring opening.
U.S. Pat. No. 4,192,567 to Gomolka is directed to a ZIF electrical connector including a male connector part having a plurality of prongs, and a female connector part including a corresponding plurality of receptacles, each containing a coiled spring. The connector includes means to expand or contract the coiled spring receptacles.
U.S. Pat. No. 5,042,146 to the present inventor discloses forming interconnecting hookup wire into a double-helix configuration. The double-helix serves as a receptacle for receiving component leads or other hookup wire ends for soldering, and also provides an integrally connected point-to-point hookup wiring alternative to printed circuit traces.
None of the above-cited references provide for zero-insertion force connection simultaneously to an inner conductor and an outer-conductor as exist in a coaxial cable.
U.S. Pat. No. 5,154,626 ("626") issued to the present inventor on Oct. 13, 1992, entitled "Double-Helix Zero Insertion Force Connector System", discloses a method to use an interleaved double-helix receptacle as a ZIF connector and is incorporated herein in its entirety by this reference. A double-helix, formed from a length of bared or uninsulated wire, includes a bridging loop which connects the two helix halves. Applying a rotational torque to the loop causes the receptacle opening to expand or contract.
The '626 patent primarily is directed to an embodiment where the male connector part includes a cylindrical contact pin which is engaged by a double-helix coil disposed within a female receptacle. A second embodiment of the '626 patent discloses a double-helix receptacle for connecting the bared center-conductor of two coaxial cables, but does not disclose a ZIF connector enabling coaxial cable ends to be easily and reliably connected so as to achieve strong mechanical connection as well as electrical connection between the two center-conductors and two outer-conductors.